Along with development of an air interface technology and continuous extension of applications thereof, reducing a transmission delay becomes one of key communication indexes in a future communication technology. For example, an end-to-end transmission delay of real-time remote computing for mobile terminals is required to be shorter than 10 ms, a transmission delay of traffic efficiency and safety is required to be shorter than 5 ms, and another service may require a shorter transmission delay.
One of key technologies for reducing a transmission delay is shortening a Transmission Time Interval (TTI). At present, the length of a TTI of the Long Term Evolution (LTE) system is 1 ms, and LTE-Advanced Release 13 (LTE-A Rel-13) has determined to start making researches on data transmission with a shorter TTI.
A short TTI has the advantage of shortening of the transmission delay, however, at the corresponding cost of high control signaling overhead and low spectrum efficiency. For a terminal with multiple types of services running concurrently, if a unified TTI is determined according to the service with a minimum delay requirement, resources may be wasted. For ensuring the transmission delay and simultaneously considering system efficiency, the terminal may be dynamically scheduled to use different TTI lengths, that is, a short TTI is used for transmission of a short-delay service, and a conventional TTI is used when another service is transmitted. Therefore, LTE-A Rel-13 makes such a requirement that compatibility with the existing LTE system should be ensured on a carrier supporting short-TTI transmission, that is, compatibility with a 1 ms TTI is required.
At present, an LTE system supports two different data scheduling manners, i.e., semi-persistent scheduling (SPS) and dynamic scheduling (DS), where SPS means that a base station indicates terminals scheduling information through high-layer signaling, including: a scheduling period, a physical resource location and a modulation and scheduling level, and after the base station sends Downlink Control Information (DCI) to the terminal to trigger the terminal for SPS, the terminal performs data communication on the same frequency resource at a fixed interval. DS means that whenever the base station determines to perform a burst of data communication, the base station sends a piece of DCI to the terminal, and the terminal performs data communication on a corresponding time-frequency resource according to an indication of the DCI, where DS has no fixed period.
In a system not supporting a short TTI, DS and SPS correspond to the same TTI. When time-frequency resources corresponding to DS and SPS are overlapped, since DS and SPS correspond to the same TTI, data incoming time, base station scheduling time, data processing time and the like corresponding to DS and SPS are all the same, a terminal may merge original SPS data and DS data together for communication. For example, the terminal merges all of the data for communication on the time-frequency resource corresponding to DS. That is, in an SPS transmission subframe, if the terminal receives DS, the DS data is received or sent (the base station packs the SPS data into the DS data).
However, when DS and SPS of the LTE system correspond to different TTIs, different data incoming time, base station scheduling time and data processing time corresponding to the scheduling make an existing working mechanism with SPS overridden by DS not applicable anymore.